Train-control system for railroads



June 11', 1929. c. s. BUSHNELL 1,717,330

TRAIN CONTROL SYSTEM FOR RAILROADS- Filed Jan. 26, 1922 2 Sheets-Sheet 2 L VENTZR Patented June 11, 1929.

UNITED STATES PATENT OFFICE.

CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAIL- WAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

TRAIN-CONTROL SYSTEM FOR RAILROALDS.

Application filed ianuary 26, 1922. Serial No. 531,903.

This invention relates to automatic train control systems for railroads.

In train control systems, it is necessary to transmit or communicate controlling influences or impulses from the trackway to moving vehicles, in order that the train control apparatus on each vehicle may be governed in accordance with the presence or absence of other vehicles, positions of switches, and other conditions affecting the safe progress of the vehicle. On account of weather conditions, problems of clearance, and like difiiculties encountered in practice, it is desirable to communicate such controlling infiuences inductively, that is, through an intervening air gap, rather than by a mechanical cooperation or physical contact between devices on the vehicle and devices on thetrack.

With a view of satisfying the principle of' failure on the side of safety, so important in railway signaling and train control systems, it is considered preferable to employ an arrangement ofcar apparatus and trackway devices which will act to produce astopping in-- fiuence in case of any failure of circuits or the like; and it is proposed to utilize the magnetic properties of an inert body of iron A on the trackway for producing the stopping influence. Since it is desirable to avoid the use of batteries or other sources of current on the trackway to put the track device into the inactive or non-stopping condition, it is further proposed to employ a track element structure which is caused to assume its inactive condition by merely closing a circuit without requiring any electrical energy.

With the type of system generally outlined above, it will be evident. that the track rails of crossings, switch points, water pans,

and similar iron and magnetic bodies along" the trackway, will tend to produce an effect upon the car equipment similar to that pro duced by the regular track elements of the system when in their active stopping con dition.. Such tendency to produce an unnecessary and false stopping control, conveniently termed rail interference, is of course, highly objectionable in systems of this character; and while various schemes for overcoming this rail interference have been suggested, it 1s proposed in accordance with the present invention to select the location and disposition of the cooperating elements on the car and on the trackway in such a way as ment adapted to communicate only one stop ping influence' Also, while such stopping influence may be employed to initiate or otherwise govern the operation of any 'suitable form of brake control or cab signal apparatus, for the purpose of explaining the nature and mode ofoperation of this IIIWEHUOH, consideration is limited to two types or forms of train control systems, namely, a permissive or semi-automatic system 1n which a brake application is initiated at each distant or caution signal unless the engmeer takes appropriate action to prevent or hold off such brake application, and an automatic stop system employing an'overlap, 1n WhlCh an absolute and unpreventable brake application is produced at each of the two danger or'stop signals in the rear of a train, Y

The various specific objects, characteristic features, and advantages of the invention will be 1n part apparent and in part pointed out as the description of the specific embodiments progresses.

In describing the invention in detaiL-reference will be made to the accompanying drawings, in which Figure 1 illustrates in a simplified and diagrammatic manner one typical arrangement and construction of trackway devices and circuits embodying this invention and designed for the permissive or semi-automatic type of system;

Fig. 2 illustrates in a simplified and conventional manner one formof car appara tus or equipment for the semi-automatic type Fig. 5 illustrates in a simplified and diagrammatic manner a modified construction of acar element and its cooperating track element;

Fig. 6 illustrates in a simplified manner a modified construction of the reset switch;

Figs. 7, 8 and 9 are diagrammatic views showing modified arrangements of the car elements and track elements.

Pemm'ssioe system.

Tmalaway eguz'pment.Referring first to the permissive or semi-automatic type of system, there is shown in Fig. 1 one typical arrangement of trackway circuits and devices adaptable for use with this type. The track rails 1 are bonded together with bond wires and channel pins or the like, in the usual way, and the track is divided into blocks of the desired length by insulated joints 2, only one block N with portions of adjacent blocks M and 0 being shown. The parts and circuits associated with each of these blocks is the same, at least in ordinary block signal territory, and for convenience these parts will be given the same reference characters with distinctive exponents. Each block is equipped with a track circuit of the usual and wellknown construction, comprising in general a track battery 3 and a track relay 4, together with the limiting resistances, battery chutes and relay boxes, all as commonly employed in practice.

It is contemplated that the railroad will be equipped with some suitable type of block signal system, manually or automatically controlled, and including the usual trackway fixed signals, either semaphore, color-light, or any other suitable type. Various forms of systems, signals and control devices and circuit arrangements suitable for this purpose are well-known in the art; and to avoid complication, there has been shown convention ally a semaphore signal J at the entrance to each block, without any attempt to show their well-known structure and controlling circuits, it being understood that these signals will be of the three-position type and will give the usual clear, caution, and stop indications, in accordance with traffic conditions in the corresponding block and in the block in advance. It may be added that the application of the train control system embodying this invention to other types of block signal systems is considered to be so evident as to require no specific illustration or description.

In the permissive or semi-automatic type of train control system under consideration, it is contemplated that a stopping impulse or influence will be communicated from the trackway to the passing vehicle at each caution signal, with or without a similar stopping impulse at a stop signal; and adjacent to the entrance of each block, traflic being from left to right (as indicated by the arrow), is a track element T, which may be located a short distance in the rear of the insulated joints 2 marking the entrance to the block or opposite such joints or a distance in advance thereof, depending upon the type of control circuits for these elements. In this particular illustration the'track element T of each block is located a short distance in the rear of the entrance thereto, and its controlling condition is governed by a line relay 5 that is controlled in turn by the-track relays of the corresponding block and the next block in advance. The control circuit for the line relay 5 of the block N, for example, may be traced as follows commencing at the common wire 6,-wire 7, relay 5, wire 8, front contact 9 of track relay 4, line wire 10 (supported on insulators on a pole line in the usual way), front contact 11 of track relay 4, wire 12 battery- 13 and wire 14 back to the common wire 6.

The track element T comprises in general a U-shaped core or yoke 15 of magnetic material and a coil 16, together with a suitable support or mounting for housing and protecting said core and coil, which will be specifically described hereinafter. The core 15 of the track element is preferably constructed of laminated iron of a good quality, so as to reduce the flow of eddy currents when a sudden change of magnetic flux takes place. The legs formed by the U-shaped core terminate in large pole pieces, the faces of which are contiguous to a plane of action which in the particular form illustrated in Fig. 2 comprises a horizontal plane disposed a considerable distance above the rails, as illustrated by the dot and dash line, The coil 16 on the track element T is connected through a front contact 17 of the corresponding line relay 5,

thus being in a closed circuit of preferably low dresistance when the line relay is enerize g Oar eguz'pment.The car element L (see Fig. 2) for cooperating with the track element T briefly described above, comprises in general a similar U-shaped core 18, one leg of which is provided with a primary or magnetizing coil P, and the other leg is provided with a secondary coil S. These legs are likewise provided with large pole pieces similarly disposed adjacent the plane of action; and the car element is located on the car to pass directly over the track element T.

In the permissive or semi-automatic type of system, the application of the brakes is accomplished in such a manner that the engineer may, by taking appropriate action, forestall or prevent the brake application. It is contemplated that the brake control apparatus will act upon the air brake systems now commonly in use; and in the typical air brake system, one simple and direct way of obtaining an automatic brake application is to forcibly shift the handle of the regular engineers brake valve to a brake applying pos'ition and hold it there. This scheme of obtaining an automatic brake application avoids any complications associated with an arrangement for causing a direct venting of the brake pipe, such as, for example, the provision of automatic means for cutting off communication between the brake pipe and the main reservoir, to allow a sufficient reduction in brake pipe pressure without interference. Also, in accordance with the principles of a permissive or semi-automatic system, it should be within the power of the engineer to release, graduate off, or actually prevent an automatic brake application, when the conditions of speed, slack, and the like make an invariable and uniform brake application undesirable; and this desirable end may be settled in. a simple manner by shifting the engineers brake valve to put on the brakes, since the brake valve handle in this instance affords the instrumentality by which the engineer may oppose or regulate such brake application, without incurring the risk of such hold-off devices being carelessly or intentionally fastened down or improperly manipulated to defeat the objects of the system, it being evident that engineers would not be likely to fasten their brake valves against movement or carelessly leave them in the wrong position.

Brake control apparatus-Various eonstructions of power devices for forcibly driving the engineers brake valve to a brake applying position can, of course, be employed, and the construction shown in Fig. 2 adapted for this-purpose has been selected 'and shown merely as a typical example, and more with the purpose of making it easy to understand the mode of operation than with the idea of disclosing the specific design preferably employed in practice.

Referring to Fig. 2, the brake controlequipment comprising the usual engineers brake valve 19, a pneumatic device K for operating the brake valve, and an electro-pneumatic valve E. P. V. are shown conventionally and designated B. On the stem of this valve 19 and under the head of its handle 20 is loosely journaled a gear sector 21 having an integral upstanding lug 22 arranged to engage the handle 20 and drive it (from left to right, as shown) to a brake applying posit-ion. Meshing with the gear sector 21 is a rack 23 suitably supported by a guide 24, and rigidly connected at the other end to a piston 25 having an air-tight fit in a cylinder 26. Between the piston 25 and one end of the cylinder 26 is a strong compression coil spring 27. In the other end of the cylinder is an adjustable stop bolt 28 arranged to engage the piston 25 and limit the throw of the sector 21 to the point where the engineers valve 19 is in the service position, or if desired, in the emergency position. Compressed air, derived from the main reservoir of the air brake system (not shown), is supplied to the lefthand side ofthe piston 25 through the control of a suitable electropneumatic valve E. P. V.

In the typical construction of the electropneumatic valve E. P. V. shown in- Fig. 2, a middle chamber 29 is connected by a pipe 30 to the cylinder 26. In the upper and lower walls of this chamber 29 are seats for poppet valves 31.and 32 carried by a valve stem 33 which is guided by upper and lower screw plugs 34. This stem 33 is urged downward from thenormal position shown by a coil spring 35 interposed between the lower wall of the chamber and a collar fixed on said stem. An enclosed space 36 above the cham-' ber 29 is connected by a pipe 38 to the main reservoir, or other source of compressed air; and the space 37 below the chamber is connected to the atmosphere through. the cxhaust port 39. The valve stem 33 is fastened to the armature- 100f an iron clad magnet having a winding 41. In order to fit in with the particular arrangement of car circuits shown, an insulated contact disk 12 is secured to the plunger of the magnet 41, and cooperates with stationary insulated contacts, preferably resilient, (shown conventionally as arrows) when the magnet coil is energized and its armature 40 and the valve stem 33 are in the raised position as shown.

The operation of the brake controlling mechanism 'just described need be outlined only briefly. Normally, that is, when the train is running under a clear signal and is not under the control of the brake governing mechanism, the coil 41 of the electro-pneumatic valve E. P. V. is energized, the valve 31 is open, and the valve 32'is closed. Compressed air now fiows from pipe 38 through open valve 31 to chamber 29, and through pipe 30 to the cylinder 26, forcing the piston 25 to the right against the opposition of the spring 27 and shifting the sector 21 to the position shown, out of the way of the handle 20 of the engineers valve 19. IVith the parts in this position, the engineers valve 19 may be moved back and forth to any of its positions without interference. When a stopping influence is communicated from the trackway in the manner hereinafter explained, the coil 2410f the E. P. V. is deenergized, and the valve stem 33 moves down under the influenceof the spring 35 and air pressure, to the lower position, closing valve 31 and opening "alve 32. The pressure in the cylinder 26 now exhausts through the exhaust port 39 at a rate determined by the size of this port, which may be made adjustable, if desired. As the pressure in the cylinder 26 is reduced, the spring 27 expands and drives the piston 25 toward the left, in turn driving the gear sector 21 and carrying with it the handle 20 of the engineers valve. The parts are proportioned or adjusted so that when the piston 25 reaches its extreme lefthand position against stop bolt 28,-the handle of the engineers valve reaches the service notch. The force with which the engineers brake valve is shifted is dependent upon the strength of the spring 27, and is wholly independent of the air pressure. The strength of this spring 27 is' preferably selected so as to overcome the opposition of friction and the latch holding of the handle 20, and positively force the valve to the service position. Such pressure, however, is preferably made small enough so that the engineer may forcibly oppose such movement or restore the valve to thelap or release position after such movement, if he so desires. Unless the engineer opposes such movement of his valve to the service position, or returns it quickly, the brake pipe is vented in the usual way through the action of the regular air brake equipment to produce a service application.

HoZd-ofi switch.-In connection with the particular type of car equipment shown in Fig. 2, there is employed a hold-off or holdby switch HS, which is preferably located where it canbe conveniently reached bathe engineer. In the simplified form illustrated, this hold-off switch HS comprises a plunger 43, with a suitable knob for facilitating its manual operation, which is supported by guides 44, and is urged in one direction (upward as shown), by a compression spring 45 interposedbetween one of these guides 44 and a collar 46 fastened to the plunger. The circuit controlling devices or contacts actuated by the plunger 43 are illustrated in a simplified manner, one set of contacts, which is normally open, comprisinga spring finger 47 suitably anchored at one end and engaged at an intermediate point by an insulated pin or stud in the plunger, so that when the plunger is moved downward, the spring finger 47 is flexed and moved into engagement with a suitable insulated stationary contact (indicated conventionally as an arrow). The other circuit controlling deviceactuated by the plunger 43 is normally closed and is constructed so as to open after the lapse of some selected interval of time following depression of said plunger. In the simplified construction shown, a contact finger 48, suitably anchored at one end, is urged downward by a tension spring 49 fastened thereto and to a suitable stationary part. The downward movement of this finger 48 is retarded by a suitable timing mechanism, which is shown conventionally as a dash-pot device. This dash-pot device comprises a cylinder 50 with a restricted exhaust opening in its lower end, adjustable in practice, in which fits a piston 51 pivotally connected to the finger. The piston 51 is provided with a flexible packing, so that when the piston moves up. ward, air may pass freely by said packing,

but when the piston moves downward, the air is confined in the cylinder and must escape gradually through the restricted exhaust port. Obviously, other timing mechanisms may be used to advantage in practice in lieu of that which has been selected for illustration on account of its simplicity. The

finger 48carries a hook-shaped stop 52, and

a flexible contact spring 53. With the finger 48 in the upper position shown, the spring 53 engages a suitable stationary contact (indicated conventionally as an arrow), and the spring is forced down some distance away from the hook-shaped stop 52. The plunger 43 carries an insulated pin engaging the underside of the finger 48.

The simplified construction of the hold-off switch HS just described constitutes in effect a manually operable circuit controller which, when operated, closes a circuit, and which, if held in the operation position longer than a predetermined time, also results in opening another circuit.

Reset swit0h.-In connection with the type of system illustrated in Fig. 2, there is employed a reset switch, designated as a whole RS. This reset switch BS is preferably located so that it is accessible only from the ground, so that before it can be operated the train must be stopped; or this switch may be enclosed in a sealed box, so that it can not be operated without breaking the seal and leaving evidence that such operation has been made; or the switch may be enclosed in a locked box, the key or keys of which are held by the engineer, conductor, or other persons,so that the switch can not be operated without a full knowledge of some responsible person or the door to the enclosing box or the switch itself, may be connected to a suitable counter or recorder, so that a record will be made of each operation of the switch. In short, this reset switch is suitably protected in such ,a way that its operation involves the stopping of the train, or considerable annoyance or publicity, or a record, or any combination of these features, the idea being that on account of the penalty associated with the operation of this reset switch, the engineer will endeavor to avoid the need for such operation by taking the appropriate actions hereinafter explained. Since it will be obvious .to one skilled in the art 110w to practice the various expedients for protecting the reset switch, no attempt has been made to illustrate any detail construction for this purpose.

The reset switch RS comprises essential- -ly normally closed contacts and normally open contacts, one set of contacts being opened when the other is closed. For reasons explained to better advantagehereinafter, it is desirable under certain conditions, to make it possible for the engineer, the reset switch to the normal osition, to gradually cut out resistance be ore closing when returning the normally closed circuit; and for this punpose, the reset switch shown-in Fig. 2, cont; prises aswitch arm 54 pivotally connected at one end and having an elongated contact piece at the other end that sweeps over the stationary. contact buttons 55 connected to resistance units. 56. The switch arm 54 may be thrown out of engagement with the contact buttons 55 and into engagement with another separate stationary button 57, this position (indicated by dotted lines) constituting the reset or operating position of the device.

Oar relays.-A suitable electro-responsive device is connected to the secondary coil S of the car element L. In the arrangement of Fig. 2, this electro-responsive device is in the form of a control relay C having an armature 58 and contact finger (shown conventionally) which is pivotally supported at its center of mass and is rocked about its pivotal axis in one direction by a suitable spring 59, and is attracted in the other direction when the coil or winding ofthe relay is energized with a current greater than the holding current for the relay. Since the specific construction of this relay and the characteristics of its design, rendering it quick acting, and sufficiently sensitive to perform its duty in this system, forms no part of the present invention, the relay C has been shown conventionally; but it should be understood that in practice this relay C will be constructed and mounted so as not to be improperly operated by the shocks, jars, and vibration to which it is subjected when carried on the locomotive or other railway vehicle, and will have the desired electrical characteristics of pick-up and dropaway conforming with the design of the other parts of the system.

While'the relay C may be employed to control the electro-pneumatic valve E. P. V. and brake control device directly, it is intended to employ a separate repeater relay R for this purpose, because the operating characteristics of the main control relay C required for proper response to the influence communicated from the trackway, do not adapt it for control of the electro-pneumatic valve E. P. V. This repeater relay R, while shown conventionally, is also designed with due regard to the duty it has to perform and with respect to the jar and vibration to which it will be subjected.

Operation of permissive system.Normal- 1y, that is, when the vehicle is traveling between control points under clear trafiic conditions, the parts and circuits of the car equipment are in the condition shown in Fig. 2. The primary coil P is energized from a suitable source' of current on the car, preferably a storage battery 60, by a circuit which may be traced as follows :commencing at battery 60, wires 61 and 62, front contact 63 of repeater relay R, wire 64, switch arm 54 of reset switch RS, wire 65, primary P, wire 66,

normally closed contact 53 of hold-by switch HS, wire 67, winding 41 of E. P. -V., wires 68 and 69 back to battery 60.

It will be noted that this circuit includes the front contact of the repeater relay R, the normally closed contacts of the reset switch RS, and the normally closed contacts of the hold-by device HS, as well as the primary coil P and the magnet 41 of the valve E. P. V. It may be explained here that the magnet winding 41 of the valve E. P. V. is connected in series with the primary coil P so as to check the flow of current through said primary coil; and the operating characteristics of the valve E. P. V. are selected so that it will be operated when the current through the .primary coil P becomes too low for safe and reliable operation, whether due to a complete interruption of the energizing circuit for said primary coil, or a high resistance break therein, or depreciation of the battery. In short, unless sufficient current flows through the pri mary coil P to insure reliable and satisfactory operation of the system, the valve E. P. V. operates and applies the brakes, vthereby controlling the train on the side of safety. Since the valve E. P. V. is to be controlled by the reception of an influence from the trackway, its inclusion in the energizing circuit for the primary coil P brings about the condition where the relay responsive to the infiuence must break the current flowing through the primary coil; and when the parts are designed for eflicient operation in practice, it is found that the desirable value for the primary coil current is too large to be effectively governed by the contacts of the main control relay C, hence a repeater relay R is preferably used.

The main control relay C is connected in circuit with the secondary coil S and the battery 60 as follows :commencing at battery 60, wires 61 and 70, front contact 71 of armature 58 of relay C, resistance 72, wire 73, secondary'coil S, wires 7 4 and 75', relay C, and wires 76 and 69 back to battery. It will be noted that this energizing circuit for the relay C includes a front contact 71 of the relay itself, making this relay a stick relay.

The repeater relay R is directly energized through the front contact 77 of the control relay C by a circuit which may be traced as follows :commencing at batter 60. Wires 61 and 70, front contact 7 7 of relay C, wire 7 8, relay R and wires 79 and 69 back to battery.

The primary coil P, being constantly energized, constitutes a source of magneto-motive-force tending to send fluxthrough the core 18 of the car element L and through the secondary coil S, but on account of the relatively large air gap between the pole pieces, the reluctance of the magnetic circuit through the secondary coil S is such that comparative- 1y little flux passes through this coil. Such ux as may pass through this coil, being constant in value, does not affect the steady current through the main control relay 0 supplied from, the battery 60.

Assume now that the vehicle, with its equipment in the normal position as shown in Fig. 2, approaches the entrance to the block N when there is another train ahead in the block 0. This other train shunts the track relay 4 of the block 0 in the usual way, opening its front contact 11 and breaking the energizing circuit for the line relay 5. When the line relay 5 drops, it opens the circuit through the coil 16 of the track element T, making this track element in effect a dead inert mass of H011.

As the car element L approaches the track element T in such active stopping condition. the magnetic qualities of the core 15 of the track element decrease the reluctance of the partial magnetic circuit-through the primary and secondary coils Pand S of the car element L. In other words, the track element '1 forms a sort of magnetic bridge for the legs of the car element L, and, partly due to the" reduced reluctance, and partly on account of the diversion of flux from leakage paths around the primary co'il P, there is arapid increase in the flux through the secondary coil S. This increase in flux, in accordance with well-known laws, induces an E. M. F. in the secondary coil S,-which will be in a direction to oppose or assist the battery 60, depending upon the way in which the secondary coil S is wound and the electrical connections. It is preferred to arrange these connections so that the induced E. M. F. produced by an increase in flux through the secondary coil S opposes the'battery. The total voltage in the circuit through the main control relay 0 and secondary coil S is thus reduced; and the parts are designed and proportioned so that the current fallsbelow the hold-up current for the relay C.

As the pole pieces of the car element L come directly over the pole pieces of the track element T, the reluctance of the magnetic circuit is a minimum and the flux through the secondary coil is a maximum. There has been, therefore, an increase in flux through the secondary coil S from a normal value to a maximum value, similar to that in the ordinary alternating current generator. Consequently, there is induced in the secondary coil S one wave or one-half cycle of voltage during the approach of the car element L to the point where it is directly over the track element T. As the vehicle advances, and the car element L recedes from the track element T, the reluctance of the magnetic circuit through the secondary coil increases, the flux dies down, and there is a change of flux through the secondary coil S in the opposite direction, thereby inducing another wave or one-half cycle of opposite polarity. In short, during the passage of the car element L over the track element T there is induced in the secondary coil S one complete cycle of alternating current, ordinarily of a somewhat distorted wave form. More particularly, the second wave or one-half cycle seems to be drawn out and tohave a lower maximum value, which is attributed to the eifects'of hysteresis and residual magnetism. For this reason, it is preferred to arrange and connect the parts so that the first wave or onehalf cycle is in the direction to oppose the battery. Another reason for employing the first wave of this cycle of E- M. F. is because, if the second-wave was relied upon for causing -a control influence, the first Wave which would occur a moment earlier would be harmful, in that, it would leave a residual effect in the magnetic circuit of the relay.

When the armature 58 of the control relay C shifts to the retracted position, it breaks the energizing circuit-for said relay at the front 7 contact 71. The main control relay C is made a stick relay in this manner in order that the slightest opening of its contacts will result in a permanent opening thereof until restored from some other control. When the main control relay C opens its front contact 77, it deenergizes the repeater relay R which opens its front contact and closes its back contact. Thus, at each caution signal the main control relay C and the repeater relay R are deenergized, with the result considered to better advantage hereinafter.

Assume that the car is in the block M approaching the entrance to the block N, and that both of the blocks N and O are not occupied. Under these conditions, the line relay 5 is energized, and the signal J indicates clear or proceed. Since the line relay 5 is energized, the coil 16 of the track element T at the entrance to the block N is in a closed circuit of low resistance. As the car element L passes over the track element T in this inactive condition, there is not produced a sufficient change of flux through the secondary coil S to cause operation of the control relay C. This is attributed to the fact that the coil 16 on the core of the track element T, being in a closed, circuit of low resistance, acts as a choke coil to oppose or choke back the passage of flux through said core.

Putting it another way, as soon as the primary coil P tries to send flux through the core 15 of the track element T, this changing flux induces in the coil 16 a voltage that, in accordance with well-known principles, tends to send a current in a direction to create a field opposing the flux inducing such voltage. In any event, it is found that by selecting the proper number of turns for the coil 16 of the track element, with regard to the strength of the primary field, sensitiveness of the relay C, and other factors, an organization may be obtained in which the inclusion of the coil 16 in a circuit of relatively low resistance permits passage of the car element without operation of the control relay C, whereas, with this coil open circuited, said relay will be operated.

1 As soon as a scheme of automatic train control is applied to a railroad, the engineers naturallly tend to rely upon the automatic system to advise them of the existence of danger conditions and perhaps slow down or stop the train for them, especially as the engineers have acquired confidence in the dependabiliiy and proper performance of the automatic apparatus. Consequently, the engineer may perhaps become more lax in the observance of the block signals, feeling that the automatic system will in some way provide a special warning or cause an automatic brake application when a signal is set against him( For various reasons, however, it is undersirable to allow the engineer to relax his vigilance in watching out for signals, or in acting upon the signal indications, or in taking his attention from the trackway. For one thing, accidents are sometimes caused by obstruction on the track, failure to observe a flag, and so on; and since these kinds of accidents are unpreventable by a train control system, it is essential that the engineer should keep a careful watch on the trackway. Also, modern block signal systems have attained a high degree of development, and are very reliable and eflicient. Similarly, engineers as a rule are highly trained, experienced, and careful operators. Hence, if the engineer becomes less vigilant in the observance of the signal 1ndications, there is sacrificed to a large extent the safety of train operation at present obtained by the aid .of the block signal system and the care with which engineers observe and obey the signal indications. Obviously, it would be better to retainall of this safety now obtained by the block signal system and the vigilant engineer, and use the automatic train control apparatus more as a supplement or auxiliary than as a substitute, so that a serious accident can occur only if the signal system, the engineer, and the train control apparatus all should fail at the same time. For these reasons it is desirable to employ the arrangement illustrated in connection with the car apparatus shown in Fig. 2.

Resumingdiscussion of the operation of the semi-automatic system of Fig. 2, the arrangement for enforcing vigilance on the part of the engineer in the observance of the caution signals operates as follows :Assume the apparatus and circuits shown in Fig. 2 in the normal condition, and the car approaching a signal at caution. For the first case, suppose that the engineer observes the caution indication of the signal, and just before passing the signal, and prior to the passage of the car element L over the track element T, presses down the plunger 43 of the hold-off switch HS. The main control relay C and the repeater relay R are deenergized as before explained; but with the plunger 43 of the hold-off switch HS depressed and its normally open contacts 47 closed, when the repeater relay R drops and closes its back contact, there is established a pick-up circuit for the main control relay C, this circuit being traced as follows :commencing at battery 60, Wires 61, 80 and 81, gong 82, wire 83, contact 47 closed, wire 84, contact disk 42 of E. P. V. and its cooperating contacts, wires 85 and 64, back contact of relay R, impedance 86, wires 87 and 75, relay C, and wires7 6 and 69 back to battery.

Upon the closure of the normally open contacts 47 of the hold-oil switch HS, there is established an alternative or additional connection from the reset arm 54 to the battery 60 in multiple with that through the front contact 63 of the relay R. Consequently, the electro-pneumatic valve E. P. V. is maintained energized by this alternative circuit when the front contact 63 of the relay R opens, provided the contacts 47 of the holdoff switch HS are at that instant closed.

It will be noted that this pick-up or holdby circuit includes the gong 82, and a normally open back contact of the repeater relay R, an adjustable impedance 86, and normally closed resilient contacts and disk 42 of the electro-pneumatic valve E. P. V. As soon as the back contact of the repeater relay R is closed, the gong 82 is sounded, and at the same time current is supplied to the main control relay C to restore it to its normal energized condition. The gong 82 does not sound when the hold-by switch HS is operated because it is shunted by the low resistance path from the battery 60, wires 61 and 62, front contact 63 and wire 64.

When the main control relay C is restored, it is maintained energized by its stick circuit; the repeater relay R is directly energized; and the electro-pneumatic valve E. P. V. maintained in the normally inactive condition by its normally energized circuit hereinbefore traced. Although the gong 82 is connected in series with the main control relay C, the operation of the gong should not inteirupt the circuit; and a gong is used in 'WlllCllilllG interrupter shunts its coils rather than break the circuit through them, or the interrupter may be entirely omitted, thereby sounding a single tap.

It is noted here that the resistance of the gong 82, the adjustable impedance 86, preferably highly reactive, together with the resistance of the contacts 47, in this hold-by circuit above traced are selected and proportioned to provide the desired amount of current through the main control relay C for restoring or picking it up, which may be larger, if

of the secondary coil S, and a front contact of the relay itself; whereas the hold-by circuit includes the impedance 86, the resistance .of

the gong 82 and the contacts 42 and 47 in lieu of the resistances in the normal stick circuit.

The normally closed contacts 42 of the electro-pneumatic valve E. P. V. are included in this hold-by circuit so that if the E. P. V. once operates to an extent to break the circuit at resilient contacts 42, the hold-by circuit is broken, and all efforts on the part of the engineer to restore the main control relay C by a simple manipulation of the hold-by switch HS will be ineffectual. In other words, the arrangement of circuits is such that the engineer can restore the main control relay 0 quickly by the operation of the hold-by switch only in case such operation of the hold-by switch is prior to and anticipates the regular operation of. the electro-pneumatic valve E. P. V., so that the engineer must operate this hold-by switch HS at the instant or before he passes the signal.

The gong 82 is employed, first, to inform the engineer when the main control relay C and the repeater relay B have dropped due to the passage of the car element L over a track element T in its active stopping condition, thereby indicating that he may release his hold-by switch HS. Second, the sounding of the gong as the vehicle passes such track element T indicates that the train control apparatus has operated-properly; and, except for the fact that the engineer has operated his hold-by device, an automatic brake application would have occurred, so that the engineer is advised at each caution or danger signal location that the system is wor ing properly.

It will be evident that, unle-s some special provisions were made, the engineer might be tempted to fasten down the plunger 43 of the hold-by switch HS, since this would then relieve him of the duty of looking out for and recognizing each caution signal. avoid this, the time controlled contacts 53 are provided. lVhen the plunger 43 is depressed.

to close contacts 47, the contact finger 48. is re leased, and is moved downward by the spring 49-gradually at a rate determined by the dashpot device 50. After the expiration of a cer tain length of time, the end of the contact spring 53 strikes the fixed retainer 52 and is drawn out of contact with its cooperating stationary contact (indicated conventionally as an arrow), thereby breaking the circuit of the magnet 41 of the electro-pneumatic valve E. P. V.,' and imposing the same train control restrictions that occur in regular operation where the engineer fails to make timely operation of the hold-by switch HS. By reason of this construction and arrangement,'if the engineer should fasten the plunger 43 down, the electro-pneumatic valve E. P. V. will be deenergized after a time and bring about the same train control restrictions that the operation of said plunger serves to avoid. In other words, if the engineer attempts to defeat the purpose of the hold-by switch HS by maliciously holding or fastening it down, he accomplishes nothing and is left in ;the same predicament that would have happened if he had left the holf-ofi' switch alone.

The dash-pot device 50 is. designed or adjusted so as to permit the plunger 43 to be held down by the engineer for a length of time suflicient to give him all reasonable latitude in passing a signal; but this time interval is preferably made so that the engineer by one manipulation can not pass two signals in succession, but must make an independent operation of the hold-off switch for each signal. In this connection, it will be noted that as soon as the plunger 43 is released and is re stored to its upper normal position b the spring 45, the finger 48 and its associate timing device are restored to theinitial condition; and if necessary, the engineer may make several operations of the hold-by switch in order to make up the time interval found necessary in approaching and passing a signal. For instance, if the engineer, misjudging his speed or distance to the signal, should operate his hold-off switch HS too quickly, he may release it, and work it again.

The operation of the hold-ofl switch HS is a simple manual movement requiring practically no exertion or annoyance. In case the engineer, however, fails to make a timely operation of this hold-off switch, he is put to a great deal of trouble and annoyance,.subjected to the censor of publicity, or discipline for records made against him, and the like. This is intended to be the penalty for the failure of the engineer to see and act upon the indication of a caution si nal, and since the manipulation of the hol -by switch HS is a very simple and easy thing as compared with the penalty, it is contemplated that the engineer, naturally doing the easiest thing, will be encouraged at least, and as a practical proposition, really forced to watch out for the signal.

In the ty i'cal arrangement in Fig. 2, the penalty for ailure to make a timely operation of the hold-by switch HS is imposed as follows :Assume that the car element L passes over a track element T in the active stopping condition, and that the hold-by switch HS has not been operated. The main control relay C and the repeater relay R drop in the same manner as previously described. The opening of the front contact of the-repeater relay R breaks the energizing circuit for the electro-pneumatic valve E. P. V. When the valve E. P. V. operates, due to the deenergization thereof, it causes application of pressure to the engineers brake valve in the same way as previously explained, tending to forcibly shift the brake valve to the service position. Also, the operation of the valve E. P. V. opens the normally closed contacts 42, and makes it useless for. the engineer to push down the plunger 43 of his hold-by switch HS. The main control relay C remains decnergized, and the application of spring pressure to the engineers brake valve continues until the reset switch RS is operated. As previously explained, access to the reset switch RS is safeguarded in some suitable way such that it can not be operated without imposing the desiredquenalty. Assume,

for example, that this reset switch RS is ac cessible only from the ground. Consequently, before the engineer can release the pressure acting on his engine brake valve, he must bring the train to astop, climb down and operate the reset switch RS. When this reset switch BS is moved down to its extreme operated position, as indicated by dotted lines, a pick-up circuit for the main control relay C is established as follows: commencing at battery 60, wires 61, 80 and 88, switch arm 54: of. reset switch RS, wire 6%, back contact of repeater relay R, resistance 86. wires 87 and 75, relay C, and wires 76 and (39 back to the battery.

In order that the engineer may not be tempted to try to defeat the objects of. the in vention by fastening the reset handle M in its operated position, provisions are made such that the reset handle 54, after having once been operated, must be restored back to its normal position before the train can proceed. It will be noted that when the reset handle 54 is shifted to the dotted line position, the normal energizing circuit through the electro-pneumatic valve E. P. V. is broken at the contact buttons 55, so that while the relays C and R can be restored to normal, the valve E. P. V. is not energized until. the reset switch handle 54 is'pushed back to the normal position.

Referring to Fig. 2, the closure of the energizing circuit for the E. P. V., which also includes the primary coil P, is preferably made by first closing the circuit through a resistance, and then cutting this resistance out stepby-step. This is done in order to avoid suddenly applying to the primary coil P the full strength of the primary current, which would send flux through the core 18 of the car element L and the secondary coil S through leakage paths. producing in the secondary coil a change of flux that, under specially unfavorable conditions, may cause operation of the main control relay C for the same reasons as the track element produces such operation. This is accomplished by the construction shown in Fig. 2, because as the engineer returns the switch arm 54 from its lower operated position (indicated by dotted lines.) he can cut out the resistance units 56 successively and gradually increase the current stepby-step through the primary coil P. making the change of flux through the secondary coil S at such a slow rate that, the voltage induced reset switch RS, it may be stated that the resistance 72 in circuit with the secondary coil S performs a similar function and prevents, or aids in prevcnting,-the drop )ing of the relay C when the full strength 0 the primary current is thrown on. Theresistance 72 is included in circuit with the sec- .ondary coil S prin'iarily for the purpose of making the effect of the impulse of induced voltage upon the relay C more uniform for different car speeds. It will be readily appreciated that the speed at which the car element L passes over the track element 'I will vary the rate of change of flux in the secondary coil S: and with certain organizations and construction of parts and circuits, it is found expedient to add the resistance 72 in order to make the effect of the impulse upon the relay C more uniform for the vary ing speeds at which the .car may travel.

Itshould be understood that the inven tion is not restricted to the use of a'i'eset switch RS specially constructed as above described. or to a resistance 72, the desired results being obtained in many cases by the resistance 72 alone. and in some cases both may be omitted. depending upon the particular design of the various devices.

Briefly summarizing the operation of the typical arrangement of the semi-auttmiatie car equipment shown in Fig. 2, when the car passes a. clear or proceed signal, the control relay C and other devices are not affected. because at this time the coil 16 on the core of the track element '1 is included in a closed circuit of low resistance, and acts. in the manner previously explained. to prevent the change in flux through the secondary coil S of the car element L necessary to cause operation of the main control relay C. Vhcn the car passes a caution or danger signal. if the engineer has observed and correctly interpreted this signal and has operated his hold-by switch S. then the electro-pncumatic valve ,E. l. V. is not dccncrgized and no pressure is applied to the engineers valve to shift it to a brake applying position, although the main control relay C drops and thegong SZ is sounded to sig nify that the apparatus 's working properly and that a cautionary control influence has been received on the car. The control of the train is left in the hands of the engineer. but it is assured that he realizes the existence of danger ahead. since he has operated the holdby switch HS and has also heard the gong sounded.

Suppose, however, that for some reason the engineer fails to see or correctly inter pret the caution signal, and consequently does not make the timely operation of his hold-by switch HS; then, the dropping of the control relay C results in deenergization of the electro-pneumatic Valve E. P. V. and the application of pressure to the engineers brake valve. The pressure applied to the engineers brake valve will, unless the engineer voluntarily and forcibly opposes movement of said valve, produce a service brake application in the usual way; and this pressure'pcrsists until the reset switch RS 13 actuated.

While the engineer may, if he desires, operate his valve against the' opposition of the spring pressure for some time and may run his train, this will be difficult, and sooner or later the engineer will find it expedient to stop and go through the performance necessary to operate the reset switch. Since the operation of this reset switch is in some of the ways, as previously explained, attended with considerable annoyance, publicity, or the like, the need for such operation constitutes a self-inflicted penalty, so to speak, for the neglect on the part of the engineer to make timely operation of his hold-by switch before passing the cautlon signal; and it is thought that such penalty Wlll result as a practical proposition in the engineer being more vigllant in watching the track and endea-voring to observe and interpret the indications of the trackway signals, thereby making the safety of the train dependent upon the vigilance and care of the engineer as well as the proper performance of the train control system.

Rail interference.In the type of inductive train control system shown in Fig. 2, the

operation of which has been heretofore considered, that is, the type of system in which the controlling influence is produced on the car by Virtue of the magnetic properties of the track element, it will be evident that a similar effect will be produced by other magnetic bodies along the trackway, such as switch points and track rails at crossings, water pans, switch stands, and the like. In the .specific type of system disclosed herein, the track element produces its effect by changing the reluctance of a partial magnetic circuit on the car and inducing in a secondary coil included in said circuit a voltage which, by opposing the normally applied voltage of a battery or other source of current, causes operation of a suitable electro-responsive device; and unless the foreign magnetic bodies along the trackway are capable, by reason of their magnetic qualities and air gap relation to the car element, of producing as great a change in reluctance of the car-carried magnetic circuit, the train control apparatus will not be operated. Since a track element is I intentionally constructed of iron with good faces must necessarily be on a level with, or

somewhat below, the tops of the track rails, in order to avoid being struck by low hanging parts of vehicles; and these limitations, more particularly if it be attempted to keep the s ace between the track rails clear for the angers of snow plows, makes the working air gap between the regular track element and the car element greater than between a track rail and said car element, with the result that the track rail has an advantage, so to speak, over the track element with respect to air gap, and may under unfavorable conditions cause a false or unnecessary operation of the train control apparatus.

While various expedients may be employed to neutralize or, minimize this rail interference, in accordance with the present invention it is proposed to dispose the track elements outside of the track rails, in order that they may have their pole pieceselevated some distance above the plane of the tops of the running track rails. With this disposition of track elements, the car element being of course located accordingly, the working plane of the car and track elements is considerably above the level of the track rails, so that the track rails and other magnetic bodies are at a disadvantage both as to air gap and to magnetic qualities, and under ordinary working conditions will not produce an influence that is objectionable. While various specific arrangements and relative dispositions of the track and car elements may be employed in practice, one typical organization which has been found adaptable to an established clearance diagram for the railroads in this country consist of mounting the car and track elements with their center lines 19 inches outside of one or the other of the running rails,

and with their working plane or center of the air gap 2 inches above the level of the top of the running rails.

In connection with this problem of rail interference, it is noted here that the coils on the car element are preferably located so that the primary coil P is ahead or leading as the vehicle travels in the normal direction of tratfic, with its pilot or regular front end leading. The reduction in rail interference occasioned by such disposition is attributed to the fact that as the primary coil passes over the track rail first, it magnetizes that track rail with one polarity, and the residual magnetism tends to oppose a rapid and strong change of flux as the secondary coil passes over this track rail, it being observed and 4),

nection with the car apparatus of the various train control systems herein described are usually well balanced in a manner which forms no part of this invention and is not shown, so as to prevent them from being ac tuated by jars, vibrations, and thelike, when carried directly by the car body, a suitable supporting means has been proposed for resisting, absorbing and transformlng such ar and vibration.

In the particular form illustrated (Figs. 3

this relay supporting device comprises a casing .132 east in the shape illustrated and preferably made upof magnetic material, so that any stray magnetism that may be present will be confined to the casing itself, rather than to the relays and other electro-responsivedevicescarrledthereby. Three perforated lugs 133 are cast lntegral with, and extend from the casing at points selected so that each of these lugs will receive sub-' stantially the same weight when the casing is supported horizontally, as shown. The holes in these lugs 133 are countersunk to receive flanged washers 13 1. A base plate 13% for supporting this relay casing 132 is provided, having bosses 136 arranged to fall directly under the holes in the projectinglugs 133. Thesebosses 136 are drilled to receive bolts 137 passing 'therethrough and through the flanged washers 134: contained on each side of the lugs 133. A spring 138 is inserted between the base plate 135 and the bottom flanged washer 134:; and another spring 139 is contained between the top flanged washer 134 and a third flanged washer 140. The top flanged washer 1 10 is then drawn downward by the aid of the nuts illustrated, thus tensioning the springs 138 and 139 and providing a resilient support for either up or down movement of the relay casing. Due to the heavy weight of the relay casing, as compared with the relays and other electro-responsive devices carried thereby, sudden jars are resisted and absorbed by the relay casing to a certain extent, and are further transformed into low period oscillations, thus protecting the relays from such sudden jars, and thereby preventing false operation and undue strain and wear of their bearings and contacts.

Modified cm and track eZements.-In Fig. 5 is illustrated another arrangement of cooperating car and track elements. These car elements are of general L-shape, and are constructed and disposed in a "ertical plane on opposite sides of the railway car, thus providing one pole piece 151 facing outward and one 152 facing downward on each side of the vehicle. The general construction of the core, coils, housing and pole pieces is similar to those just described, and therefore these par.- ticular parts have not been shown in detail.

The track element shown in Fig. 5 for cooperating with the car element is of peculiar U-shape construction, having its legs and pole faces disposed at right angles to each other so that these pole faces 153 and 154 will be disposed substantially parallel to and in cooperative relation with the pole faces of the L-shaped car element. These track elements are mounted in heavy wooden blocks 155 along the side of the track in any manner to rigidly and permanently connect them with the track rails. Since such mounting may take any one of a variety of forms wellknown in railway construction, no particular manner of so supporting the track element with respect to the track has been illustrated. In this form of cooperating car and track elements, a magnetic body, before it can appreciably influence the partial magnetic circuit of the car element, has to lie in an inclined plane corresponding to the pole pieces of the track elcment; and since switch rails, and other magnetic bodies ordinarily encountered, do not have such 'a peculiar location or dispositiomthere is practically no opportunity for rail interferences.

In addition to the several specific constructions and arrangements of car and track elements shown and described, various other forms will be obvious to those skilled in the art. It will be observed that the car element and track element are essentially two isolated partial magnetic circuits arranged to fit together and afford a complete magnetic circuit of low reluctance. The specific shape of the magnetic cores affording such partial magnetic circuits may, of course, be considerably varied. In order to avoid rail interference, the working plane between the car and track elements, regardless of the specific form of these elements, should be kept above the level of the track rails, and as far as practicable, out of the range of influence of other magnetic bodies along the track. \Vithout further discussion, it will be readily seen that these working principles may be carried out by numerous specific structures, other than those shown and described.

Reset s'1.0if0hFi 6.In this Fig. 6 there has been illustrated a modified form of reset switch, which is similar in its operation to the reset switch illustrated in Fig. 2. This modified reset switch is, however, automatic in gradually cutting out the resistance inserted when the pick-up switch is operated. This reset switch comprises a pivoted bar 183 provided with insulated end contact pieces, and a handle. This bar 183 is biased to its normal position as illustrated by a spring 184, thus normally maintaining an electrica connection'between the wires 64 and 65 b the bridging of the conducting strip 185 Wit the uppermost stationary contact button 55.

Two other stationary contact buttons 186 are provided and positioned so that when the handle is operated to the dotted line position these contact buttons will be bridged, thus connecting the wires 64 and 88 for resetting the train control appgratus. When this reset switch has been operated, it will not 1mmedi ately return to its normal position, but Wlll gradually come back and gradually cut out the resistance 56, and cause a gradual increase of current in the primary coil of the car apparatus. This gradual return or retarded action is due to the presence of a timing device, which for simplicity has been shown as a dash pot 187 constructed and operating the same as the dash pot device 50 associated with the hold-by switch HS in Fi 2 and previously explained. The adjustahle vent of this dash pot 187 in practice will be adjusted so that the resistance 56 will be cut out gradually enough, so that the inductive effect produced by the increasing current in the pr1- mary coil will not be suflicient to actuate the repeater relay R by the induction of an E. M. F. in the secondary coil. This reset switch is thus partially automatic, in that, after it has been operated to reset the apparatus, it connects the primary coil'in series with a resistance, then gradually cuts out this resistance without any further attention on the part of the operator.

Against traffic m0vements.ln the practical operation of railway trains on double track roads, occasionally a train makes a backup or against traffic movement, that is, travels in a direction opposite to the normal direction of traflic for which the track is signalled. In such a case, it will be evident that the train will put the track elements ahead of it in the active stopping condition, since the train, itself, occupies the track circuits controlling these track elements before it reaches them. Consequently, if the car equipment and track elements are in a relation to cooperate when the train makes such an against traffic movement, a stopping influence will be communicated at each signal. By arranging one car element on one side of the car with respect to its front end, say the right hand side, and then disposing all the track elements on the corresponding side of the track with relation to the normal Cllrctk' tion of traflic, when the car runs head-on opposit-e to the normal direction of tratlic. the

car element is on the opposite side of the track from the track element, and the train control system does not interfere with a backup move under such conditions. However, in the permissive or semi-automatic type of brake control apparatus under consideration, an automatic brake application may be easily prevented under the circumstances by a simple manipulation of the hold-by devices previously explained, so that with this type of systern, it i unnecessary for all ractical operating conditions to make any particular provisions for against traific movements, such the car or on the track. so that they cooperate when the locomotive is traveling either end ahead.

Fig. 7 shows an arrangement in which the car elements are duplicated, one on each side of the locomotiverand the primary and secondary coils of these car-elements are connected together in series, so that the cooperation of either with a track element will communicate the stopping influence.

If desired, an arrangement of circuits, which will be obvious to those skilled in the art that needs no particular illustration may be employed, whereby the secondary coils of the car elements on opposite sides of the locomotive may be alternately connected in circuit with the control relay, or the audion by a switch connected to andoperated by the regular reversing lever of the locomotive, or the reversing handle of the electrical car controller in the case of an electrically propelled car, or to any other changeable part responsive to the direction of-rotation of the wheels.

Fig. 9 illustrates a similar arrangement in which the track elements are duplicated, the coils of these track elements being connected in series and controlled by a front contact of the line relay in the same way as a single track element, or the coils of these track elements may be connected in separate closed circuits of low resistance governed by separate front contacts of the line relay. hen two car elements on opposite sides of the locomotive are employed, it may be found expedient to also duplicate the track elements, in order to utilize to best advantage the existing car equipment and produce a stronger influence. Such an arrangement is shown in Fig. 8.

While there have been shown and described various specific constructions and arrangements of parts and circuits for practicing the invention, and the mode of operation and many ofthe advantageous features of these constructions have been pointed out, it should be understood that this disclosure does not exhaust all of the various embodiments of the invention, nor include the various auxil.

iary devices and methods of signal and train operation well-known in the art and commonly practiced. The specific disclosure herein is, therefore, susceptible of considerable adaptation and modification in practice, without departing from the invention.

What I claim is 1. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle by the inherent properties of a magnetic body, comprising in combination, a car-carried receiving element extending lengthwise of the car and adapted to receive a control influence when passing adjacent an inert magnetic body, said receiving element having its lowermost part disposed a distance above the running rails so as not to receive a control influence when passing over intersecting track rails; and a track element including an inert magnetic body located lengthwise of and above the running rails and still low enough to come under said receiving element, and transmit a control influence to said car-carried receiving element when said track element is in its danger influence transmitting condition.

2. Means for transmitting control influences from the trackway to a moving railway vehicle comprising, a car-carried element comprising a magnetic body having two depending legs, a secondary coil on one of said legs receiving a control influence when passing adjacent an inert magnetic body, said element being mounted on the vehicle with the lower ends of its legs a distance above the running rails so that no control influences will be received from intersecting track rails throughout the commercial range of car speeds, and a track element comprising. a magnetic body having a winding thereon normally contained in a closed de-energized circuit and mounted above the running rails so that the car carricd element passes thereover and receives a control influence from said track element if the car element passes over the track element and the winding of said track element is open circuited, but no such influence will be transmitted if said winding is closed in a circuit of low resistance.

3. Influence transmitting means for train control systems comprising, a car-carried receiving element including a magnetic body having two depending legs each having a winding thereon, one of said windings having a current induced therein when passing adjacent a magnetic body, said car element being mounted outside of the running rails with its poles a distance above intersecting track rails so that no control influence will be received from such rails, and traflic controlled trackway devices each comprising'a body of magnetic material when in its active condition disposed above the top of the running rails and so that the car-carried receiving element of a passing car passes thereover for causing such control influences to be transmitted when said track devices are in their rails so that no control influence will betransmitted when passing over intersecting track rails, and track elements having the properties of a body of iron when in their effective conditions positioned above the running rails and with respect to the trackway so that the car element will passthereover and will cause the transmission of a control influence from a track element to a passing car element when such track, elementis in its eflective condition.

5. In an automatic train control system, in combination with the usual engineers brake valve, of means to actuate said brake. valve comprising, a cylinder having a piston therein, means directly connecting said piston to said brake valve, adjustable means for limiting the movement of said piston in one direction in said cylinder, a spring acting on the piston to move the brake valve to the brake applying position, and an electro-. pneumatic valve having a normal and a danger position for connecting said cylinder with a source of compressed air to oppose the force of said spring when said electro-pneumati'c valve is in its normal position, and for releasing said air when in its danger position.

6. In a train control system according to claim 5, in which the spring is of such strength that it may be forcibly resisted by the engineer.

7. In a train control system comprising, spring means for actuating the usual engineers brake valve which spring means exerts a force which may be resisted by the engineer, apiston movable by the spring, adj ust- I able means for limiting the movement of said piston by said spring, means for opposing the force of said spring under normal conditions, and means governed by traific controlled trackway devices for releasing said last mentioned means.

8. Car-carried apparatus for automatic train control systems comprising, a car element of magnetic material having a primary winding for producing a. magneto-motiveforce therein, and a secondary Winding for receiving a control influence, a control relay connected to said secondary winding and adapted to be actuated by impulses generated in said winding, and resistance connected in series with said secondary winding and said relay to cause amore uniform eflect of said impulses upon said relay throughout a certain range of car speeds.

9. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle inductively comprising, a normally energized influence receiving means, a normally energized train control device controllable by said influence receiving means, and manually operable means including a signal which if actuated will prevent said influence receiving means from actuating said train control device, and will give a signal when an influence is received by said influence receiving means.

10. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising, means for receiving control influences from the track- Way including a normally energized stick relay, a normally energized train control device adapted to be controlled by said stick relay, and manually operable means for preventing said stick relay from actuating said train control device when said stick relay is de-energized due to the reception of a control influence from the trackway and including means for again picking up said stick relay, said manually operable means being ineflective to pick up said stick relay until said stick relay has assumed its de-energized condition.

11. In a train control system of the type in which control influences are transmittedfrom the trackway to the vehicle through an intervening air gap comprising, means for receiving control influences from the trackway including a normally energized stick relay, a normally energized train control device adapted to be controlled by said stick relay, and manually operable means for preventing said stick relay from actuating said train control device when said stick relay is de-energized in'response to control influence received from the trackway including means for sounding an alarm andfor again picking up said stick relay, said manually operable means being ineffective to pick up said stick relay until said stick relay has as sumed its de-energized condition.

12. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising, means for receiving control influences from the trackway including a normally energized stlck relay, a repeater relay, a normally energized train control device adapted to be actuated by said stick relay, mean'swhich if operated will pick up said stick relay before said train control device has been actuated by the deenergization of said stick relay due to the reception of a control influence, and resetting means including a back Contact of said repeater relay for picking up said stick relay after said train control device has been actuated.

13. In a train control system according to claim 12, in which the resetting means is only accessible after a penalty has been inflicted upon the engineer.

14. In an automatic train control system comprising, car-carried equipment having a primary winding and asecondary winding, a control relay connected in a stick circuit in series with said secondary winding, and an electrically operated train control device connected in series with said primary winding and controlled by said control relay, and means for momentarily energizing said control relay and then gradually cutting in the current in said primary Winding.

15. In a train control system according to claim 14, in combination with means for antomatically gradually cutting in the current in said primary Winding after said control relay has been momentarily energized.

, 16. Influence communicating means for train control systems comprising, a car-carried element consisting of a magnetic body having two depending legs terminating in a plane located a predetermined distance above the top of the track rails, an influence receiving coil on one of said legs in which a voltage is induced due to a change of flux through said one leg, and a trackway device disposed so that a car-carried element of a passing car passes thereover and comprising a magnetic body when in its active condition and bridging the legs of said car element through an intervening air gap, said air gap being smaller than the distance between the top of the track rails and the aforesaid plane.

17. Influence communicating means for train control systems comprising, a car-carried element of magnetic material having depending legs, a normally energized primary Winding on one of the legs, a secondary winding on another leg, said elementhaving its legs terminating in a plane located a predetermined distance above the track rails and trackway means comprising an inert body of iron when in its active condition to induce a current in said secondary winding and located below the path of said car-carried element and a distance above the track rails which is less than the distance between said car-carried elementand a plane through the top of the rails of the trackway.

18. In an automatic train control system, the combination with a railway vehicle, a vehicle carried element having depending legs terminating in a plane a predetermined distance above the top of the track rails, a sec ondary coil on one of said legs. a control relay connected in astick circuit in series with said secondary coil and a source of energy,

a trackway element comprising an inert mass of iron when in its active condition for inducing voltage in said secondary coil, said trackway element having upstanding legs terminating in a plane above the top of the track rails and adapted to cooperate with said vehicle carried element, and train control mechanism controlled by said relay.

19. In an automatic train control system, the combination with a railway vehicle, a vehicle carried element comprising an iron yoke, a normally energized primary coil and a secondary coil on said yoke spaced a distance apart to allow the larger part of the flux from said primary coil to take leakage paths not linking the secondary coil, the lowermost part of said yoke being located a considerable distance-above the top of the rails, a control relay connected in a stick circuit in series with said secondary coil and a source of energy, a trackway element comprising an inert mass of iron when in its active condition for inducing a voltage in said secondary coil, said track element extending above t-h'efl top of the rails so as to have an influence transmitting advantage over that of the track and crossing rails, and train control mechanism governed-by said relay.

20-. In an automatic train control system, the combination with a railway vehicle, a vehicle carried element comprising an iron yoke having a normally energized primary coil thereon, a secondary coil on said yokespaced a considerable distance from said prinary coil, said vehicle carried element having its lowermost part located a considerable distance above the top of the rails, a control relay connected in a stick circuit in series with said secondary coil and a source of energy, a trackway element comprising an inert mass of iron when in its active condition located in the path of said car element and extending a distance above the track rails so as to have an influence transmitting advantage over track and crossing rails, said track element transmitting a control influence by 'momentarily deenergizing said said relay due to the diversion of flux from leakage paths about the primary coil through said secondary coil, and train control mechanism controlled by said relay.

21. Car-carried apparatus for automatic train control systems comprising, a car element of magnetic material having a primary winding for producing a magnet0-motiveforce therein and a. secondary winding for receiving control influences, a control relayv connected to said secondary winding and adapted to be actuated by impulses generated in said winding, and trackway means for -in ducing a voltage in said secondary winding .under danger traflic conditions due to movement of the car element by said track element, the ratio of ohmic resistance to inductance of the circuit including said relay being such that a substantially uniform influence is transmitted throughout a certain range of car speeds.

22. Car-carried apparatus for automatic train control systems comprising, a car element of magnetic material having a primary windingifor producing a magneto-motive force, a secondary winding for receiving control influence, a control relay, a source of direct current, and a circuit including said relay, said secondary C01l, said'source and a front contact of said relay, and trackway means for inducing a voltage in said secondary coil under danger traflic conditions due to passage of said car element by said trackway means, the ratio of the resistance to the inductance of said circuit being such that a substantially uniform influence is transmitted throughout a certain range of car speeds.

23. In an automatic train control system, thecombination with a brake control apparatus on a vehicle, normally energized control means on the vehicle automatically influenced from the trackway for initiating operation of said apparatus, said control means if momentarily deenergized remaining deenergized until restored, manually operable means on the vehicle adapted to maintain saidbrake control apparatus inactive inde-- pendently of the control thereof by said control means providing it is operated prior to the initiation of the operation of said control means, a signal on the vehicle, and means for actuating said signal and restoring said control means when said manually operable means is operated and a control influence is transmitted from the trackway.

24. An automatic train control system comprising, a brake applying meansacting on the usual air brake system, automatically actuated control means (Ethe type which if momentarily changed will remain in the changed condition until restored for governing said brake applying means, means on the vehicle manually operable by the engineer for pre-,

venting actuation of said brake applying,

means and for restoring. said control means and eifectlve only if actuated before the control means is initiated, and means only accessible from the ground for resetting said brake applying means to normal.

25. An automatic train control system ac-- cording to the preceding claim, further characterized by the provision of means to penalize the engineer if the manually operable means is moved to its effective position for more than a predetermined interval of time.

26. An automatic train control system comprising, automatic brake control apparatus acting on the usual air brake system of a railway vehicle and adapted to apply the brakes upon the reception of a danger influence from the trackway dependent on trafiic conditions ahead including a stick relay, manually operable "means effective only for a predetern'nued'time and only if actuated prior to the v reception-of such danger influence for preventing an application of the brakes by said apparatus and for restoring said stick relay, and signaling means actuated by said danger influence providing said manually operable means has been actuated, to indicate communication of the danger influence.

a 27. Car-carried equipement for automatic train control systems comprising, brake control apparatus acting on the usual air brake equipment, a relay connected in a stick circuit for governing said apparatus and adapted to be actuated by a control influence from the traclnvay, a manually operable device eilective only if actuated prior to the reception of such control influence to prevent the actuation of said apparatus and to restore said relay, said manually operable device being effective only for a predetermined 'period of time after its initiation to prevent such actuation, and means accessible only from the ground to restore said apparatus back to norlnal 2S. (ar equipment for automatic train control systems comprising, a car element having a normally energized primary winding and a secondary winding, a brake control device connected in a circuit with said primary winding. a normally energized control relay connected in a stick circuit with said seconda ry winding for governing said brake control device whereby the transmission of an inductive influence to said secondary winding will cause permanent dcenergization of said control relay. and means for resetting said control relay including means for gradually energizing said brake control device and said primary winding.

which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising; means for receiving control influences from the trackway including a normally energized stick relay; a repeater relay: an electrically operated train control device; an'energizing circuit for said repeater relay including a front contact of said stick relay; an energizing circuit for said repeater relay including a front contact of said stick relay; an energizing circuit for said train control device including a front contact of said repeater relay; a normally open auxiliary energized circuit for said train control device including the Winding thereof and a signal. in series; a normally open pick-up circuit for picking up said stick relay; and manually operable means for closing said auxiliarycircuit and said pickup circuit; said manually operable means when operated being effective to close said auxiliary circuit and said pick-up circuit for a period of time only; whereby said train control device may be maintained in its energized condition in spite of de-energization of said stlck relay and repeater relay as evi- "denced by actuation of said signal due to cuit for said train control device including a front contact of said repeater relay; a normally open auxiliary energizing circuit for said train control device including the Winding of said train control device, and audible signal and a back contact of said repeater relay, in series; and manually operable means for closing said auxiliary circuit and for picking up said stick relay; said manually operable means being eifectivefor a predetermined period of time only for each operation thereof; whereby said signal is sounded while said train control device is maintained energized through'said auxiliary circuit.

31. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising; means for receiving control influences from the trackway including a normally energized stick relay; a repeater relay; an electrically operated train control device; an energizing circuit for said repeater relay including a front contact of said stick relay; an energizing circuit for said train control device including front contact of said repeater relay; a normally open pick-up circuit for said stick relay includinga'back contact of said repeater relay; and manually operable means for completing said pick-up circuit; said manually operable means being effective for a period of time only-for each operation thereof.

32. In a train control system of the type in which control influences are transmitted from the trackWay to the vehicle through an intervening air gap comprising; means for receiving control influences from the track- Way including a normally energized stick relay; a repeater relay; an electrically operated train control device; an energizing circuit for said repeater relay including a front contact of said stick relay; an energizing circuit for said train control device includ ing a front contact of said repeater relay; a normally open pick-up circuit for said stick relay including a back contact of said repeater relay, a front contact of said train control device and an audible signal, in series; manually operable means effective for a time only for each operation thereof for completing said pick-up circuit; whereby said audible signal is only energized While said repeater relay is de-energized, said train control device is energized and said manually operable means is in its operated condition.

33. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising; means for receiving control influences from the trackway including a normally energized stick relay; a repeater relay; an electrically 0perated train control device; an energizing circuit for said repeater relay including a front contact of said stick'relay; an energizing circuit for said train control device including a front contact of said repeater relay; a normally open auxiliary energizing circuit for said train control device including the Winding of said train control device, an audible signal, a back contact of said repeater relay and a front contact of said train control device, inseries; and manually operable means for closing said auxiliary circuit, said manually operable means if left in its active condition eventually actuating said train control device.

34. In a train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising; means for-receiving control influences from the trackway including a normally energized stick relay; a repeater relay; an electrically operated train control device; an energizing circuit for said repeater relay including a front contact of said stick relay; an energizing circuit for said train control device includmg a front contact of said repeater relay; a normally open auxiliary energized circuit for said train control device including the winding of said train control device, an audible signal, aback-contact of said repeater relay, a front contact of said train control device and a protective contact, inseries; and manually operable means which if operated closes said auxiliary circuit, said manually operable means if operated opening said protective contact after a time. i

35. In a train control system of the intermittent type comprising; means for receiving control influences from the trackway including a normally energized stick relay; an electro-responsive device energized through a circuit including a front contact of said stick relay; brake control means governed by said electro-responsive device and maintained inactive while said electro-responsive deviceis energized; a normally open pick-up circuit for said stick relay including an audible signal and a back contact of said electroresponsive device; a manually operable means for closing said pick-up circuit; said manually operable means being effective for a time on y for each operation thereof; whereby said audible signal is only energized while said manually operable means is operated and said electro-responsive device assumes its de-cnergized condition.

36, In a train control system of the intermittent type comprising; means for receiving control influences from the trackway'ineluding a normally energized stick relay; an electro-responsive device energized through acircuit including a front contact of said stick relay; brake contrdl means governed by said el'ectro-responsive device and maintained inactive While said electro-responsive device is energized; a normally open pick-up circuit for said stick relay, including an audible signal and a back contact of said electroresponsive device, in series; and manually operable means for closing said pick-up circuit; said manually operable means if held in its operated position, eventually efl'ecting operation of said brake control means 37. In a traincontrol system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising; means for receiving control influences from the'trackway including a normally energized stick relay; a repeater relay; an electrically operated train control device; an energizin cir- 95 cuit for said repeater relay including a ront contact of said stick relay; an energizing circuit for said train control device including 'a front contact of said repeater relay; a normally open auxiliary energizing circuit for 100 said train control device including the windin g of said train control device and an audible signal, in series; I and manually operable means for closin said auxiliary circuit and for picking up said stick relay; said manually 106 operable means being eflective to pick-up said stick relay only after said stick relay has assumed its de-energized position and only for a predetermined period of time for each operation of said manually operable means, 110 whereby said signal is sounded at least for the time required for the stick relay to assume its de-energized position and again assume its pickedup position.v

In testimony whereof I hereby aflix my signature.

CHARLES s. BUSHNELL. 

